ML20198D228
| ML20198D228 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/20/1986 |
| From: | Standerfer F GENERAL PUBLIC UTILITIES CORP. |
| To: | Travers W Office of Nuclear Reactor Regulation |
| References | |
| 0426A, 426A, 4410-86-L-0081, 4410-86-L-81, NUDOCS 8605230193 | |
| Download: ML20198D228 (2) | |
Text
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'h GPU Nuclear Corporation g
gf Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057-0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
(717) 948-8461 4410-86-L-0081 Document ID 0426A May 20,1986 TMI-2 Cleanup Project Directorate Attn:
Dr. W. D. Travers Director US Nuclear Regulatory Commission c/o Three Mile Island Nuclear Station Middletown, PA 17057
Dear Dr. Tcavers:
Three Mile Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 Clarification of Basis for Technical Specification Change Requests 49 and 51 with Respect to Control Room Emergency Air Cleanup System Following extensive discussions with the NRC TMICPD, GPU Nuclear re-evaluated its initial proposal, as transmitted in TSCR #49, to delete certain functions of the Control Room Emergency Air Cleanup System. GPU Nuclear now intends to retain the full operability requirements for this system. However, based on our analysis, the results of which were provided in GPU Nuclear letter 4410-86-L-0033, dated February 26, 1986, GPU Nuclear terr.ains steadfast in its proposal to delete the requirement for a backup onsite AC power supply for this system. The requirement for backup power is no longer warranted based on the current plant status and non-essential nature of the TMI-2 Control Room function. The purpose of this letter is to provide further clarification of the latter point.
As noted in the referenced letter, our analyses to date have demonstrated that there is no credible accident at TMI-2 which would challenge the habitability of the TMI-2 Control Room. The most limiting radiological event identified was a TMI-1 LOCA accompanied by a concurrent loss of offsite power (LOOP).
Subsequent analysis demonstrated that the probability of occurrence of a simultaneous TMI-l LOCA and TMI LOOP was so low as to not warrant special compensatory measures.
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PDR GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
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Dr. 3,rav;ro May 20,1986 4410-86-L-0081 Although the proposed deletion of the requirement for emergency backup onsite AC power appears to be justified based on the improbability of occurrence of an event which would require such a capability, the proposal is underpinned by the following factors. First, the interval during which the Control Room Emergency Air Cleanup System would not be operable as the result of a LOOP probably would be brief.
Second, no active components are required to maintain the current safe shutdown conditions of the plant.
Finally, since the postulated event originates at TMI-1, there is no requirement for TMI-2 Control Room personnel to become directly involved in accident mitigation.
Therefore, for that brief interval during which the Control Room Emergency Air Cleanup System would not be operable as a result of the combined TMI-l LOCA and a TMI LOOP, temporary evacuation of the Control Room and the remainder of the TMI-2 power block would be a viable alternative. Further, short term access to TMI-2, including the Control Room, could be accomplished by use of self-contained breathing apparatus or similar protective devices, as appropriate, to counter temporary hazardous conditions. Over the longer term, continuous manning could be restored by initially limiting shift staytimes and expanding the interval between shift rotation until normal intervals are re-established.
In summary, GPU Nuclear has concluded that continuous manning of the TMI-2 Control Room is not required to respond to the postulated limiting radiological event, maintain the current " safe shutdown" condition of the plant or protect the health and safety of the public during an emergency event at TMI-1.
As soon as possible after notification of an emergency event at TMI-1, ongoing recovery activities at TMI-2 would be terminated and all systems placed in a safe configuration. Within its limits, the Control Room Emergency Air Cleanup System would provide protection from a TMI-l event.
In the unlikely event that concurrent TMI-l LOCA and TMI LOOP compromise the habitability of the Control Room, temporary evacuation could be effected since no actions would be required to be taken in the Unit 2 Control Room to maintain TMI-2 in a " safe shutdown" condition or to protect the health and safety of the public. Thus, the maintenance of an onsite emergency backup AC power supply is not warranted for the specific purpose of ensuring the operability of the Control Room Emergency Air Cleanup System and, thus, the continuous habitability of the Control Room.
Sincerely,
)
. R. Standerfer Vice President / Director, TMI-2 FRS/JJB/cck